In the cell, proteins are synthesized by the ribosome. After formation of the peptide bond, the protein Elongation Factor G (EF-G) catalyzes the translocation of the ribosome/tRNA/mRNA complex to the next codon in order for continued elongation of the protein chain. EF-G is a GTPase that binds to ribosomal RNA, and it interacts with ribosomal proteins. The hydrolysis of bound GTP is necessary for the release of EF-G from the ribosome, and then the creation of the next peptide bond can occur. How EF-G binds the ribosome and catalyzes translocation at the molecular level remains unknown. The long-term objectives of this research are to: 1) characterize the interaction between EF-G and ribosomal RNA using biophysical techniques, and 2) gain a greater insight into the mechanism of GTP-dependent ribosome translocation. Therefore, we aim to solve the atomic resolution X-ray crystal structure of EF-G in complex with specific domains of ribosomal RNA and GTP analogs. These crystal structures will be analyzed in terms of how conformational changes in EF-G bound to rRNA and the hydrolysis of GTP by EF-G, are coupled to elongation during protein synthesis.